Us Mailaccess.txt -

IP ranges and domains permitted for direct relay.

Support for secure handshake protocols, ensuring that only authenticated clients can query the mail store. US MAILACCESS.txt

Deployment of TXT records in the DNS to mitigate Man-in-the-Middle (MITM) attacks during mail transport. IP ranges and domains permitted for direct relay

Session duration limits for IMAP/POP3 connections to prevent resource exhaustion. 5. Implementation Notes US MAILACCESS.txt

Since "US MAILACCESS.txt" is not a recognized formal standard, it likely refers to a local technical configuration file or a draft document for an internal or Simple Mail Transfer Protocol (SMTP) implementation.